For java experts -help me please

I am a computer science student and I work on Web-based project that depeneds on JSP, JAVA and MYSQL. There are 2 types of users who will use the system of my project: customers and staff.My doctor ask me to add some features to my project.
One of these features is privacy of customers' telephone numbers.

I want to allow market staff to call the customer without know his telephone number (for privacy issue).And if a customer calls the market, market staff just see his name.

*I know that there are programs (e.g. Skype) that are used to call from the computer to the telephone number but I want to retrieve the telephone number from the database and call the customer without seeing his number.

please help me how I can do this task and if there is available java code that
do this task or website that may help me

Ok, if all your data is in a database, it's not difficult. In the phone call method, make a query to get the phone number depend on user name. It's your logic pal. Mainly it's not Java. Got it? Any confusion on what I say?